Activity for TonyStewart
| Type | On... | Excerpt | Status | Date |
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A: Control logic for mosfet in piezoelectric energy harvesting circuit Every real part has resistance including your piezo current source. Every switch resistance is a loss in energy (I^2 R t)=E and includes diode and transistor switches. What you need, I think, is to incorporate MPT theory into your block diagram and use a goal of matched impedances to achieve it. ... (more) |
— | 1 day ago |
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A: estimation of pogo pin resistance I agree with Olin that unknown contact area is the biggest variable. I think the scientific way is to test and verify each contact using a 4 pin kelvin bridge. The sum of 2 pins carrying constant current can be measured as voltage by 2 adjacent pins on pads sufficiently large. It probably wo... (more) |
— | 2 months ago |
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A: What type of button is this on a remote control It is interesting to see how they deposited these carbon electrodes over solder mask and copper traces both under the button foil switches and membrane switches alike which offer more tactile feel. Both offer capacitance changes to non-conductive switches. The membrane switches are mounted on their... (more) |
— | 2 months ago |
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A: Can I make an AC inductor (reactor) rated 75mH 40A from a 3-phase induction motor? The 70.9/40.8 A rating for L.R. is rated only for ; Locked rotor time 19s (cold) 11s (hot) I doubt this meets your requirements unless you modify from a forced air cooling motor to a pumped liquid cooling system. I'd contact a local oil-filled transformer supplier and get an autotransformer. ... (more) |
— | 4 months ago |
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A: CAN BUS monitoring with a LED You'll need a differential comparator, something like what was suggested in here. Imagealttext But I'd look for a proper Canbus Rx and extract that to convert to single ended one shot to pulse for activity. (more) |
— | 4 months ago |
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A: Ceramic capacitor "memory" effect? I have never seen this slow drift in ceramic caps, yet I have seen fast memory effect drift in S&H designs using high Dk ceramic capacitors in the 70's. So I have learnt that all ceramic caps have memory effects (except low Dk C0G/NP0's). The capacitance also changes with DC voltage, so Ic= VdC/dt +... (more) |
— | 5 months ago |
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A: What fabrication process is being used for jellybean parts As of the early 2020s, common technology nodes for SSI (Small-Scale Integration) and MSI (Medium-Scale Integration) ICs include nodes such as 180nm, 130nm, 90nm, 65nm, 45nm, and 28nm. Each technology node represents a specific level of lithographic resolution that costs billions to create. Migrating... (more) |
— | 5 months ago |
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A: Driving LED with NPN transistor from I/O pin If you choose suitable ultrabright LEDs , there is no need to use 40 mA. I have over 10 thousand LEDs all over 16,000 mcd at 20 mA which is painfully bright for close indicator but works well 100 m away. They are also all matched brightness and Vf within 10%, but I ordered these special for a high ... (more) |
— | 7 months ago |
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A: derating MLCC ripple current for transient current spikes Remember that RMS measurements assume at least 1 cycle or in your case 100 ms or 10 Hz. So the Ripple Current/rms vs Temp rise is always valid for any duty cycle. This means in theory you can raise the current significantly since the spike is a very low duty cycle. In practice, the device will have... (more) |
— | 7 months ago |
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A: Will shorting a lithium ion battery cause an explosion? > Will shorting a lithium ion battery cause an explosion? Chain Reaction: The release of flammable gases can lead to a chain reaction, where the heat generated by the short circuit causes even more heat, which in turn generates more gases. This cycle continues to escalate the temperature and press... (more) |
— | 7 months ago |
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A: Why 3.3V instead of 3V? The other answers are excellent justification to the the industry standards imposed on CMOS logic. The historical migration to smaller lithography CMOS led to lower Cds values which led to faster rise times or higher toggle f's. However realize that the standard has been undocumented standards of 50... (more) |
— | 8 months ago |
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A: What is Ground Electrode in EMG? CMRR design is key to rejecting grid e-fields that impose noise onto EMG, EKG,EEG amplifiers. This includes all series Zs of cable balance and Amp CMRR. For this reason >100 dB CMRR are required using INA's and not OA's with 1% R's (-40dB error). The same CMRR matching is required on 60/50 Hz... (more) |
— | 8 months ago |
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A: Essential safety features of an EMG/medical grade device? Current limiting input differential Rs of 1M into a 10M INA with clamp diodes make this a simple task. (more) |
— | 8 months ago |
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A: Power switches and automotive load dump, unclamped The spec 79V 0.5 ohm 5ms = 62.41 Joules . The TVS must be rated for a low temp. rise at this energy dump or higher. MOV's are limited by the number of discharges as the oxide wears out, but may be used if size appropriately for desired MTBF. (more) |
— | 8 months ago |
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A: Can the corner frequency of thermal noise change with change in source impedance? Any time you have a dielectric interface ( pF ) source resistance will always have an error in signal response until the electrode impedance is eqal or less than the sub-cutaneous impedance. This will affect the expected 1/f noise response. Your goal is to reduce Rs and increase Cs with gel and ... (more) |
— | 8 months ago |
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A: Confusion in operation of analog computer The two-terminal symbol for the attenuator comes from 3 pin potentiometer (pot.) referenced to 0V = "GND" Image alt text The summing amplifier is always inverting and gives you 3 options for gain which means internally it uses a 3 pin pot. to choose the gain for you based on the ratio of resist... (more) |
— | 11 months ago |
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A: Over-voltage protection for device with photovoltaic cell source This IC is not well suited for the task. MPPT (Maximum Power Point Tracking) relies on matching impedance according to the maximum power transfer theorem. However, in the case of a photovoltaic array (PV), it functions as a current source with a voltage limit (Voc) and a short circuit limit (Isc).... (more) |
— | 11 months ago |
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A: What are these transformer graphs about? For R loads I is in phase with V. For L loads , V lags I up to 90 deg. For C loads, I lags V up to 90 deg. The trigonometric tangent angle is the ratio of impedance: Real to reactive. Your lectures or ref. book will give all the details. (more) |
— | 11 months ago |
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A: How is it possible to perform a open circuit test on a induction motor? In an open circuit test, also known as a no-load test, an induction motor is operated without any mechanical load connected to its shaft. The purpose of this test is to determine the no-load losses, core losses, and magnetizing current of the motor. General Purpose: efficiency and performance ... (more) |
— | 11 months ago |
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A: what should the output be for this use case of the CD4047 chip? Possibly it is damaged. Be ESD aware and do not power up with any voltage on any pins > 0.5V (Latchup failure) If raising p9 (reset) does not lower Q to logic "0"=<20% Vdd) replace the IC. No sweat, be more careful next time for handling failures of ESD etc. Most new IC failures are hand... (more) |
— | 11 months ago |
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A: Why arc welding does not require high voltage to arc? - gas tubes, SCRs, and welder arcs all have negative incremental resistance. This means when conduction begins, the resistance drops like a crowbar and is sustained until the current drops below the holding current. - thus a typical ambient breakdown voltage for a sharp point of 1kV/mm is the sa... (more) |
— | about 1 year ago |
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A: What does it mean for a signal to have impedance? $$Z = R + jX $$ R is a real resistance that stores energy as heat and temperature rise which depends on the thermodynamic property of thermal resistance which is impacted by an enclosure to get hotter or cooler by forced airflow. Everything has some real resistance, even insulators with an elec... (more) |
— | about 1 year ago |
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A: Testing instrumentation amplifier with differential signal It is important to realize that an ECG signal is high impedance and this easily picks up line voltage E-fields. Using a 50 Ohm sig.gen. is a poor simulation of the use of this circuit and also negates any common mode rejection using it as a single-ended amplifier with one input grounded. Ground by ... (more) |
— | about 1 year ago |
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A: What is the difference between rise/fall time and Turn-On/off Delay Time? To understand the timing, you must understand the cause. Delay is the time from input to output It is measured from +10% of input to 90% of output ( or a 10% change in output), unlike logic chips where the same voltage is used for input and output so delay is measured at Vdd/2 or 50% from input to... (more) |
— | over 1 year ago |
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A: Minimizing Common Mode Radiation - Separating Grounds The problem with cable emissions from HS data and SMPS noise is very common even with UTP and ribbon cable with adjacent grounds on differential signals. I have seen this frequently on HDD testing at EMC sites, whereas the HDD emits nothing of interest. The problem is due to the imbalance of the... (more) |
— | over 1 year ago |
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A: Ceramic filter vs ceramic resonator A resonator cannot replace a filter because the filter has multiple resonances to extend the bandwidth. For AM carrier modulation using a narrow band resonator with 0.5% tolerance of 6MHz or +/-30 kHz with a Q of 10k and its narrow -3dB BW can be as high as a crystal resonator but > 100 worse tol... (more) |
— | over 1 year ago |
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A: Low-pass filter after the output DAC in CD players The oversampling is said to simplify the LPF yet the better reason is that it improves the SNR. Lower noise comes from better image rejection, lower filter ringing, and significantly lower group delay distortion in the audio band as the band edge is moved up. The majority of phase shift trav... (more) |
— | over 1 year ago |
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A: pH Electrode Buffer - Offset when solution grounded DC offsets in hundreds of mV from different grounds may be coming from either the floating ground or the PE earth. The latter may be from rectified AC line filter noise shunted to PE. The former might be caused by front-end ESD protection diode rectification with DC bias and a CM signal large enough... (more) |
— | over 1 year ago |
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A: Can confusing the plugs for earphones and microphones do any damage? If you mean electret microphone, no damage to JFET buffer. Microphone input won't damage a headset with it's current limited pullup resistor for electret Mics. (more) |
— | over 1 year ago |
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A: Design high -pass filter with 2 points of the bode plot Filter design 101 - 1. given hypothetical high-pass (HPF) filter -3dB gain HPF at fc 2. attenuation of -8dB at fc/2 3. Assumptions gain = 0 dB at f>> fc 4. Ripple between -3dB and 0 dB is unknown but assume 0dB max for simpler case. 5. steepness of skirts << fc is unknown but we know 1s... (more) |
— | over 1 year ago |
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A: Circuit which create ac sine wave from dc pulsed signal This is about as simple an analog inverter that I can simulate, but warning, not for the beginner with resonance issues. The bridge diodes are 2f multipliers reduced to logic level with divide by 2 FF, then complementary inversion switches with a center tapped transformer with the tap having the i... (more) |
— | over 1 year ago |
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A: Results of analysis of Hartley oscillator dont make sense This LC circuit depends on several criteria for stable linear oscillation; - 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or 360 deg at gain >=1 Thus each reactance affects fo. - adequate bias current and impedance ratios with... (more) |
— | over 1 year ago |
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A: What reactance actually is? Reactance is the lossless part of impedance that stores and releases energy E=1/2 LI^2 or 1/2CV^2 . Much like a spring stores energy when compressed or expanded. L is a conductor that stores current with charges flowing. Q=LI. C is an insulator with some dielectric constant , Dk, relative to a... (more) |
— | about 2 years ago |
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A: When do I need to put anti-aliasing filter in front of SAR ADC? Anti-Aliasing filter depends on the following parameters; 1. Signal BW 2. Sampling Rate 3. Sampling duration and thus BW of sample 4. LPF attenuation of alias spectrum above 1. From your SNR spec or dynamic range desired for resolution When sampling rates of 64x are used, ofte... (more) |
— | about 2 years ago |
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A: Capacitor ESR vs. Impedance Capacitors are lossless with 0 ESR and rise in temperature and become less reliable by 50% for every 10’C rise due to I^2ESR=Pd losses. However the current spectrum must be known with the ESR frequency graph in order to estimate losses. The ultimate goal is to attenuate ripple voltage by the imp... (more) |
— | almost 3 years ago |
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A: Is there a way to reliably measure antenna return loss outside a lab? The RSSI detector in the receiver is the best field tool. In Windows I had a tool (Wifi Radar?) that read the Broadcom IC RSSI and displayed a time plot of the results as I changed laptop orientation a couple of degrees and the results might change from -74 to -84 dBm and result in occasional errors ... (more) |
— | almost 3 years ago |
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A: Why are antenna PCB traces square instead of rounded? Corners and chambers that are a small fraction of a wavelength are not significant in the <4Ghz band. More significant is the tolerance and loss tangent on the substrate. They would hardly be measureable even with a 2 ps TDR. Emissions are not significantly different. WHAT COUNTS is the RL and lo... (more) |
— | almost 3 years ago |
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A: Estimating the input capacitance of an BLDC motor controller To answer some of your questions: Cable inductance: - - approx 1uH/m +/-50% depends slightly on l/d ratio , while cable impedance from sqrt(L/C) depends on twists/ft 50pF/m while coax is 100pF/m Bulk storage Cap - - C value should store Energy Ec for load power x sag time between puls... (more) |
— | almost 3 years ago |
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A: How to estimate time of completion while developing an electronic product? In my 15 yrs of intense deadline R&D for new state-of-the-art design in my 45yrs experience, estimation of time is inversely proportional to the number of mini failures from bad assumptions from which you learn to expand your understanding of everything. You don’t have to be brilliant, that helps imm... (more) |
— | over 3 years ago |
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A: How to plot the I-V curve of a tunnel diode? How to test a Tunnel diode in 25 words or less. - With DC bias = 490mV with fine tuning and a small signal swing of 60mV you can generate a IV negative slope of -16 Ohms. (more) |
— | over 3 years ago |
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A: Using FET based followers and design rules Allow me to address the MOSFET only as a source follower. - this has very unpredictable linear use without voltage = current feedback as the RdsOn at threshold has a wide tolerance.(>20%) (Many wider than the next example). However it is extremely popular in dual N ch. designs for a Half Bridge ... (more) |
— | over 3 years ago |
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A: Microwave oven interfering with WiFi on the 2.4GHz band Microwave Materials, Spectrum then EMI effects on SNR of WiFi, BT. There are a lot of measurable parameters in microwave dielectrics which affect; - Dielectric Constant , Dk between conductors and thus Impedance , Zo - scattering parameters in a transmission path from mismatch and losses ... (more) |
— | over 3 years ago |